Self-aligning pitman-bearing box



Feb. 1', 1927. 1,615,940 l V. L. FORSYTH SELF ALIGNING FITMAN BEARINGBOX Filed Sept. 21, 1925 Patented Feb. 1, 1927.

UNETED STA'S VALORIS L. FORSY'I, OF FORT WORTH, TEXAS.

SELF-ALIGNING PITMAN-BEARING BOX.'

Application led September 21, 1925. Serial No. 57,527.

web type of pitman as compared with a tubular type.

A further object of the inventlon 1s to mount the box on its fulcrum pinso as to be free to shift laterally as well as to rock on said fulcrumpin, thus preventing twisting of the wrist pin and assuring a free andsmooth action.

A construction designed to carry out the invention will be hereinafterdescribed to-` gether with other features of the invention.

r1`he invention will be more readilyl understood from a reading of thefollowing specification and by reference to the accompanying drawings,1n which an example of the invention is shown, and wherein:

Fig. 1 is a side elevation of a pitman hav ing a bearing box thereinconstructed in accordance with my invention,

Fig. 2 is a side elevation of the same, a port-ion of thevpitman beingomitted, i

Fig.4 3 is a vertical sectional view with the stirrup omitted,

lFig. 4 is a cross-sectional view .taken on the line 4 4 of Fig. 1,

Fig. 5 is a cross-sectional view taken on the line 5-5 of Fig. 1,

Fig. 6 is a cross-sectional view taken on the line 6-6 of Fig. 2, and

-Fig. 7 is a sectional view' showing the rib 'in the box opening of thepitman.

In the drawings the numeral 10 designates a. pitman, which as is shown(Fig. 6) is H- shape inA cross-section, but which may be made of any ofthe web shapes commonly used in structural beams. Near the lower end ofthe pitman a rectangular opening 11 is provided by cutting out the web.stirrun 12 is suitably attached to the upper end of the web. A bearing`boxcomprising an upper member 13 and a lower member 14 and divided atits transverse center, is mounted in said opening. Each member has asemi-cylindrical seat 15 for receiving a bearing member 16 of suitablemetal. The members 16 when assembled provide a cylindrical bore orbearing surface. The details of the foregoing parts may vary accordingto the conditions of use and manufacture.,

1n order that the box may rock or oscillate the lower member has areducedboss 17 disposed transversely of the bore of the bearing members16. 'The boss has a longitudinal concaved recess 18 in its undersurface, whereby the boss may fulcrum on a pin19 extending transverselythrough the pitman and suitably secured therein. Sufficient clearance inthe opening 11 around the box is provided so that the box may' rockfreely. Au important feature of the invention resides in the flaringsides 18 given to the recess 18. the outer ends and permit the box toshift or oscillate laterally to either side on the pin, as well as torock in a vertical plane on said pin.'

These sides Hare from the centerto In preparing the vpitrnan 10,vertical ribs i 11 (Figs. 1 and 7) are provided on the side of theopening 11 where the web is cut out. These ribs are rounded offtransversely and act to limit shifting of the box longitudinally of thepin 1.9, thus eliminating end play of the box, but permitting freehorizontal and vertical movement as described.

A Wrist pin 20 of the usual construction has its collar 21 bearingagainst the end of the box. For holding the members of the box togethera wedge 22 is passed through slots 23 in the pitman parallel to the pin19. The upper member 13 of the box has a transverse groove 24 providedwith a convex bottom cut on a radiushaving its center (fo-iucident withthe center of the pin 19. The under edge of the wedge is curved toconform `to the contour of the bottom of the groove. y

The wedge is driven in to hold the box and its bearing members incontact with the wrist pin 2O and a cotter pin 25 is passed through oneof a series of holes 26 in the wedge to keep thelatter in place. It willbe seen that the box mayl rock on the pin 19 because the bottom of t egroove 24 will ride under the wedge. This oscillation will be ample tocompensate for any variation of the pitmanl from its perpendicularposition with relation to the wrist pin. The flaring recess 18 willcompensate any twisting movement by permitt-mg the box to shifthorizontally on the pin 19, thus avoiding breaking of the wrist pin orinjuring the pitman. It is obvio'us that the bearing box is adequatelysupported center of the bore to and a proper bearing is had for theWrist pin 20. Whenever the pitman is distorted the box will retain itsalignment with the wrist pin 20, thus avoiding undue friction, strainsand breaks.

Various changes in the size and shape of the different parts, as Welllas alterations and modifications may be made within the scope of theappended claims. 'The pitman need not be tubular or flattened, but maybe otherwise constructed to receive the box.

What I claim, is:

l. The combination with a. pitman, of a fulcrum pin mounted therein, awrist pin bearing box having a concave rocking seat upon its under facefor circumferential movement upon said pin and the sides of said seatbeing ared from its center outwardly to form a bearing point to permitsaid box to oscillate transversely. to the axis of said pin, and meansfor holding the box in the pitman against vertical movement relal tiveto the fulcrum pin but permittingrocking movement thereon.

2. The combination with a pitman, of a fulcrum pin mounted therein, awrist pin bearing box having a concave seat .upon its under side forcircumferential rockingupon said pin and the sides of said seat beingflared in opposite directions to form a central bearing to permit saidbox to oscillateN transversely to the axis of said pin, and a fasteningdevice in the pitmanA with which the upper portion of the box hasrocking-'enf gagement.

3. The combination with a pitman having an opening and vertical ribs oneach side' thereof, of a wrist pin bearing box mounted in the opening ofthe pitman and having its ends terminating at the ribs thereof, a bossyupon the lower portion of the box having a lengthwise bearing at a rightangle to the bore of the box and a flared side wall having va bearing ats1 listantially the longitudinal ermit said box to oscillatetransversely of its lengthwise bearing, a transverse fulcrum pin .in thepitman engaging the lengthwise and side wall bearings of the boss topermit oscillation upon eiier bearing, and means for retaining the uponsaid pivot of the box,

bearing box in engagement with said fulcrum pm.

4. The combination with a pitman having an opening, of a wrist pinbearing box mounted in the opening of the pitman, a boss on the lowerportion of the box having a lengthwise bearing at right angles to thebore of the box and provided with a transverse pivot intermediate theends of said bearing, a transverse fulcrum pin in the pitman mounted tooscillate in said bearing or the upper portion of the box having agroove with a convex bottom, and a fastening member mounted` in thepitman and engaging in said groove, the groove having a width greaterthan the thickness of the fastening device to allow the box to rock.

5. The combination with a pitman, of a wrist pin bearing box having arocking seat in its under side, a fulcrum pin mounted in the pitman andengaged in the seat of the box, said seat being formed to permit the boxto rock circumferentially upon the pin and to oscillate transversely tothe axis of the pin by a pivot thereon, means for holding the box incontact wit-h the pin, and means engaging the sides of the box forpreventing movement of the box axially of the `pin while permitting thecircumferential and transverse movements of the box.

6. The combination with a pitman having an opening and vertical ribs oneach side of the opening, of a wrist pin bearing box mounted in theopening of the pitman, having. its ends terminating atrthe ribs of thepitman opening, a boss on the lower portion of the boxl having a flaredrecess at right angles to the bore of the box, a transverse fulcrum pinin the pitman engaged in the recess of the box, the upper portion of thebox having a grooveI with a convex bottom, and a fastening membermounted in the pitman and engaging in said Groove, the groove having awidth greater than the thickness of the fastening device to allow thebox to In testimony whereof I aix my signature.

VALORIS L. FORSYTH'.

